Carbon content control of SiOC film with methane containing plasma

Abstract

The deposition of SiOC thin films via remote plasma atomic layer deposition (RPALD) was investigated. In the experiment, the recipe was composed by adjusting the ratio of Ar and CH4 plasmas to control the carbon content in the SiOC thin film. OMCTA (Octamethyl cyclotetrasiloxane) was used as a precursor during the deposition process at 200, 300 and 400 ° C and Ar, CH4 plasma was used as a reactant. Plasma and deposition temperatures cause a significant impact on the physical and electrical properties of the film. When Ar and CH4 plasmas were used during the deposition process, the film contained carbon and exhibited a low dielectric constant. In addition, when Ar and CH4 plasmas are used as reactants, Si-C bonds in the thin film form pores and lower ionic polarization to lower the dielectric constant. As a result of FTIR, the higher ratio of CH4 plasma, the more cage structure in the thin film. Among the Si-C bonds, the cage structure increased the film density compared to the Si-CH3 bond. In Ar plasma, the dielectric constant was 3.2 and in CH4 plasma, the dielectric constant was 2.6. In both plasma conditions, the dielectric constant was lower than SiO2 film with dielectric constant of 3.9. On the other hand, XPS analysis showed that SiO1-C3 and SiC4 bonds appeared in the film deposited with CH4 plasma, which did not appear in the film deposited with Ar plasma. These bonds affected the physical and electrical properties of the thin film.